Method for preparing a masterbatch of natural rubber and silica

Abstract

Method for preparing a silica/natural rubber masterbatch, including: doping the silica with magnesium; preparing at least one dispersion of the resulting doped silica in water; bringing a natural rubber field latex into contact with the aqueous doped-silica dispersion and mixing them together so as to obtain a coagulum; recovering the coagulum; and drying the recovered coagulum so as to obtain the masterbatch.

1 . A method for preparing a masterbatch of silica/natural rubber comprising:
 doping a silica with magnesium thereby obtaining a doped silica;   preparing at least one dispersion of the resulting doped silica in water;   bringing a natural rubber field latex into contact with the aqueous doped-silica dispersion and mixing them together, thereby obtaining a coagulum;   recovering the coagulum; and   drying the recovered coagulum, thereby obtaining the masterbatch.   
     
     
         2 . The method according to  claim 1 , wherein recovering the coagulum comprises filtering. 
     
     
         3 . The method according to to  claim 1 , wherein the recovering of the coagulum comprises centrifuging. 
     
     
         4 . The method according to  claim 1 , wherein the silica is a precipitated silica. 
     
     
         5 . The method according to  claim 1 , wherein the following condition is satisfied: the level of magnesium doping of the silica is greater than or equal to (0.2×pH-1.4). 
     
     
         6 . The method according to  claim 5 , wherein the following condition is also satisfied: the level of magnesium doping of the silica is less than or equal to (0.2×pH-0.8). 
     
     
         7 . The method according to  claim 6 , wherein silica upon bringing the two dispersions into contact with each other is present in an amount between 20 phr and 150 phr (parts per one hundred parts by weight of elastomer). 
     
     
         8 . The method according  claim 7 , wherein the amount of silica upon bringing the two dispersions into contact with each other is an amount between 30 phr and 100 phr. 
     
     
         9 . The method according  claim 8 , wherein the amount of silica upon bringing the two dispersions into contact with each other is an amount between 30 phr and 90 phr. 
     
     
         10 . The method according  claim 9 , wherein the amount of silica upon bringing the two dispersions into contact with each other is an amount between 30 phr and 70 phr. 
     
     
         11 . The method according to  claim 1 , further comprising adding an aqueous coupling agent dispersion before or upon bringing the aqueous magnesium-doped silica dispersion into contact with the natural rubber latex. 
     
     
         12 . A masterbatch of silica/natural rubber prepared according to  claim 1 . 
     
     
         13 . The masterbatch according to  claim 12 , wherein the silica content is between 20 phr and 150 phr. 
     
     
         14 . The masterbatch according to  claim 13 , wherein the silica content is between 30 phr and 100 phr. 
     
     
         15 . A masterbatch according to  claim 14 , wherein the silica content is between 30 phr and 70 phr. 
     
     
         16 . A rubber composition based on at least one silica/natural rubber masterbatch prepared according to  claim 1 . 
     
     
         17 . A finished or semi-finished article comprising a rubber composition according to  claim 16 . 
     
     
         18 . A tire tread comprising a rubber composition according to  claim 16 . 
     
     
         19 . A tire or semi-finished product comprising at least one rubber composition according to  claim 16 .